Rapid screening for bacterial colonies harbouring tandem hepatitis B virus sequences by an oligonucleotide probe

Transfection of the hepatitis B virus (HBV) genome requires the cloning of tandem HBV sequences into a plasmid vector, which is usually screened for by restriction enzyme digestion of plasmid minipreparations from at least a dozen bacterial colonies. We describe a simple alternative screening method based on in situ hybridization of bacterial colonies with a [32P]-labelled synthetic oligonucleotide which spans the head-to-tail junction site of two tandem HBV molecules. The accurate detection by the oligoprobe is confirmed by enzymatic digestion.